Note 12 - Segment Information - Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net revenues	$ 17,352	$ 10,823	$ 47,420	$ 29,955
Earnings before income tax expense	2,841	1,721	8,349	2,594
Net earnings	2,018	1,090	5,541	1,657
Corporate, Non-Segment [Member]
Earnings before income tax expense	(292)	(55)	(1,841)	(848)
Net earnings	(186)	(34)	(1,158)	(549)
Thermal Products [Member] | Operating Segments [Member]
Net revenues	11,470	6,641	28,440	17,429
Earnings before income tax expense	1,539	1,402	4,735	2,709
Net earnings	1,183	888	3,228	1,737
EMS [Member] | Operating Segments [Member]
Net revenues	5,882	4,182	18,980	12,526
Earnings before income tax expense	1,594	374	5,455	733
Net earnings	$ 1,021	$ 236	$ 3,471	$ 469